A data storage system may form all or part of a network-based provider of cloud-based storage or computing services. Such a data storage system may include one or more data storage machines (e.g., server machines) with various data storage drives (e.g., disk drives, flash drives, or other storage drives). Data storage machines and their drives may be physically organized (e.g., arranged) into one or more racks (e.g., of machines, devices, or both). Data storage machines and their drives may be logically organized (e.g., configured) into one or more volumes (e.g., logical volumes) of data. The various data storage machines may be configured to operate as a single data storage system.
A data storage system may implement data replication (e.g., making one or more copies of data objects) to improve fault tolerance. For example, in the event that a data object (e.g., a data volume or a block or sector of a disk drive) becomes unusable (e.g., due to data corruption, network outage, or hardware failure), a replicated copy of that data object may be used instead.